In-situ spectroscopic analysis of sub-second switching polymer electrochromes
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Authors
David Liu
Andrew Chilton
Pengjie Shi
Michael Craig
Steve Miles
Aubrey L Dyer
Vincent Ballaraotto
John Reynolds
Issue Date
Type
Journal Article, Professional Journal
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Abstract
As electrochromic polymers can switch with a high transmittance contrast in the sub-second time frame, an analytical tool to rapidly probe the electrochemically-induced optical transition is required for characterization of these materials for electronic displays and smart windows. A novel technique is described to synchronize the electrochemical and optical measurements by utilizing an external trigger to facilitate coordinated communication between the potentiostat, which applies a voltage to the electrode supported electrochromic polymers, and the optical spectrometer that records the induced optical transitions. By using a spectrometer containing a photodiode array detector, these measurements are capable of rapid data acquisition to track the electrochromic change in the polymer films, with as many as 500 spectra captured during a one-second switch of the polymer from a colored, neutral to highly transmissive state. Additionally, with this rapid, full-spectral measurement, it is possible to trace the temporal evolution of the electrochromic change to determine the presence of intermediate color tones, as well as their duration. Here, three polymers are shown, ECP-Magenta, ECP-Green, and ECP-Black, which obtain high transmittance contrast between 40 to 50 Δ%T, with sub-second switching times measured in the range of 400 to 700 ms, demonstrating their potential for use in electrochromic windows and displays where rapid transitions are desired.